Anvers University. Belgium: Researchers at the University of Antwerp demonstrate a clear link between obesity and oocyte quality. The number of obese people is growing all the time. But a
recent finding suggests that egg cell quality may also be impaired as a
result of being overweight or obese. Researchers in the Department of
Veterinary Sciences at the University of Antwerp came to this conclusion
and pointed the finger at saturated fatty acids as one of the main
culprits.
“Animal models demonstrated that a diet rich in saturated fats and
poor maternal health may influence the micro-environment of maturing
eggs”, says Professor Jo Leroy from the Laboratory of Veterinary
Physiology and Biochemistry (University of Antwerp). "Importantly, the
changes that were identified in blood also occur in follicular fluid, so
the growing and maturing oocyte may sense this change. In the lab, for
example, we discovered that consuming too many saturated fatty acids
during an egg’s last maturation phase can seriously affect its
development and have a negative impact on embryo quality after
fertilisation, with all the resulting consequences."
In her doctoral research, PhD student Sara Valckx studied whether
there is also a correlation between weight, follicular fluid composition
and egg cell quality in humans. Her research saw her working closely
with a number of reproductive health centres, which provide IVF
treatment, among other services.
The highly sensitive egg cell
“In women, too, the composition of follicular fluid reflects what is
going on in their blood”, Valckx explains. "Moreover, our results
indicate that egg quality in obese women is impaired. To examine this in
more detail, we even exposed bovine egg cells in test tubes to
follicular fluid from obese women. What we noticed was that these egg
cells did significantly less well than those that were exposed to
follicular fluid from women with a normal BMI."
This research yet again confirms that egg cells are highly sensitive
to changes in their micro-environment. "Impaired egg cell quality can be
directly linked to reduced embryo quality and to lower chances of
successful implantation and subsequent pregnancy", Valckx emphasised.
“We must remain critical, of course”, adds Professor Leroy: “Our data
are obviously based on women who attended a reproductive health centre,
because that is the only place we could obtain follicular fluid. Our
assumption, however, is that this group is representative of the general
population of obese women."
Saturated fatty acids
“We wondered what the explanation for this impaired egg cell quality
could be. Our research indicated that the concentrations of saturated
fatty acids in the follicular fluid of these obese women were higher
than usual, so we decided to examine this in more detail", says Leroy.
"Higher free fatty acid concentrations are a typical indication of a
metabolic health problem, something we frequently see in patients
suffering from obesity or type 2 diabetes, due to the increased
breakdown of fats and associated metabolic changes."
Valckx: "We cultivated mouse follicles in test tubes for two weeks
and tried to mimic the development and maturation of egg cells and
ovulation in humans. During the culture process, we added increased
concentrations of fatty acids to simulate the process we had discovered
in obese women."
The conclusions proved both simple and clear: "The follicles
developed but we immediately noticed that the quality of the egg cells
which matured in those follicles were substandard. The proportion of
eggs that developed into embryos was lower and the metabolism of those
that did go on to form embryos was affected. We see that these effects
are mainly caused by saturated fatty acids."
A number of recently launched research projects are now studying this
phenomenon in greater detail: "Most of all, we want to learn more about
the development of such impaired embryos and what the potential
consequences are for a child's health", says Leroy.
More information?
Professor Jo Leroy: Jo.leroy@uantwerpen.be and 0485 76 71 17.
Url: http://www.uantwerpen.be/en/rg/vpb/